As the photomask technology advances toward further miniaturization, the pattern feature width becomes smaller than the exposure wavelength. Use is now made of the resolution enhancement technology (RET) such as optical proximity correction (OPC), modified illumination, immersion lithography, phase shift method, and double exposure lithography. In particular, the phase shift method has heretofore utilized halftone phase shift films having a transmittance of about 6%. To form a pattern of narrower width, for example, to form a pattern with a half pitch of up to 50 nm by photolithography, a halftone phase shift film having a higher transmittance is necessary for gaining a higher contrast ratio. Specifically a halftone phase shift film having a phase shift of about 180° and a transmittance of 9% to 40% is required.